Judith Potts was an actress and is now a voice, acting and presentation coach. She is married with two children, three stepchildren and is the proud grandmother to two grandsons. She lives in west London and Yorkshire. In 2008 she was diagnosed with breast cancer. She can be contacted at judith.potts@telegraph.co.uk and is on Twitter @JudithPotts.

How much influence do we actually have on whether we develop breast cancer?

Research suggests that women who have big babies are more likely to get breast cancer

I sometimes think that women cannot win. First of all, research told us that a childless woman has a higher risk of developing breast cancer. Now we read that having a big baby doubles the mother's risk of developing the disease later in life – but that risk can be reduced by having more than one child.

Then there was the report that pregnant women whose working life involves standing for long periods of time, like teachers, shop workers and cleaners – and working long hours – give birth to babies with lower birth weights and smaller heads.

A "big" baby weighs in at 8.25 lbs – but can a pregnant woman determine the weight of her baby? I know there are far too many obese mums-to-be and, with the extra weight go pregnancy complications but, as someone who weighed 7 stone 12 before becoming pregnant and who had "morning sickness" 24 hours a day with both my pregnancies – rarely managing to hold down a complete meal – I was amazed to give birth to babies weighing 8 lbs 2 ozs and 8 lbs 6 ozs. Two "big" babies – and, exactly as the research discovered, 30 years later I developed breast cancer. Although – hold on a minute – shouldn't my second baby have reduced the risk?

A couple of years ago, scientists at the Karolinska Institute in Stockholm suggested that girls who were underweight at the age of seven ran the risk of developing breast cancer – but that girls of the same age who were slightly overweight were less likely to develop particularly aggressive and difficult to treat tumours. Surprisingly, the research also showed that the latter group were less likely to develop the disease in the menopause years. I was definitely an underweight seven year old and, as I have written before, so was my closest friend. We both developed breast cancer – she, very sadly, did not make it to her 50th birthday.

So – where does all this conflicting research leave us? How important really is our size – or our babies' size – in preventing or developing breast cancer? Obesity is a huge and growing problem in the UK, not least for obese women with breast cancer.

"Size does matter when it comes to breast cancer treatment", says Dr Julia Wilson, head of research at Breakthrough Breast Cancer. "We can improve survival for obese women if we know which drugs are more likely to work for them, and avoid those which are less likely to succeed. We want each breast cancer patient to get the right treatment for their specific needs – and this is a step in the right direction."

Dr Wilson was referring to research carried out by Breakthrough Breast Cancer, The Institute of Cancer Research and the Royal Marsden NHS Trust which shows that, even after successful treatment with aromatase inhibitors (aromatase is the enzyme which is complicit in raising levels of oestrogen – the "baddie" in over three quarters of breast cancers, which need the hormone to grow the cancer) the oestrogen levels in obese women – although markedly reduced – are still double those of normal weight women. Does this mean that for every extra pound goes a rise in oestrogen levels? Is it that simple?

I am not sure. There are so many possible scenarios on which to speculate, but how much influence do we actually have on whether or not we develop breast cancer? Whatever we do, we need to win.